Welded Repairs According to ASME PCC-2
- Posted by: arvengtraining
- Category: Welding Codes and Standards Piping Pressure Vessels

ASME PCC-2 is a post-construction code that provides comprehensive guidelines for the repair and alteration of pressure equipment and piping, covering both welded repairs and mechanical repairs. For the safety of both the system and the personnel involved in its repair and maintenance, it’s important to adhere to the guidelines laid out in the code.
Section 2 of the code covers the repair of pressure equipment and piping using various welding techniques. When equipment is already in service and requires restoration or strengthening without replacing the entire component, these repairs are critical and are governed by the rules and recommendations in this code, specifically for equipment that was designed according to other ASME codes, although if no better options are available, it may be applied to equipment designed according to other codes.
The following are the key areas covered in ASME PCC-2 for welded repairs:
1. General Requirements
ASME PCC-2 outlines general requirements for performing welded repairs, and includes the following considerations:
Qualification of Welders and Procedures: Welding procedures, welders, and welding operators shall be qualified in accordance with the requirements of the applicable construction code or post-construction code.
Material Compatibility: The material used for the repair must be compatible with the base material of the pressure equipment. Chemical composition, strength, and thermal expansion must all be considered when choosing the repair material. The repair materials should meet or exceed the mechanical properties of the original materials (has at least equal notch toughness and allowable stress), to ensure they do not weaken the structure.
2. Preparations for Welding
Proper preparation is crucial to ensure the welded repair’s effectiveness. The guidelines for welding preparation include:
Surface Preparation: Prior to welding, the surface of the component must be free of contaminants like rust, oil, or dirt, which could impair the weld quality. If necessary, the surface must be cleaned to remove these contaminants.
Preheat Requirements: Some materials, in particular high-strength steels or materials with high hardness, may require preheating before welding to avoid cracking or other such defects. ASME PCC-2 outlines when and how preheating should be done.
Post-Weld Heat Treatment (PWHT): Depending on the material and the nature of the repair to be carried out, post-weld heat treatment may or may not be necessary. PWHT is used to relieve stresses induced by welding, improve toughness, and reduce the potential for cracking and crack propagation.
3. Welding Techniques and Methods
ASME PCC-2 provides recommendations for welding techniques and methods that may be suitable to carry out these types of repairs. They include considerations such as:
Types of Welding: The welding technique to be used (e.g., Shielded Metal Arc Welding (SMAW), Gas Tungsten Arc Welding (GTAW), or Submerged Arc Welding (SAW)) will depend on the repair requirements and type of material. The code may specify which processes are acceptable for different materials or repair scenarios.
Weld Size and Geometry: The weld size and geometry should be sufficient to restore the structural integrity of the component. Guidelines include minimum and maximum weld sizes, as well as the requirements for correct shape and profile.
Weld Repair Location: Certain areas may be more challenging to weld or may be more critical for system integrity. The repair location must be assessed to ensure that the welding technique used is suitable for the pressure and temperature conditions of the area.
4. Inspection, Examination, and Testing of Welds
After the weld is completed, it’s essential to thoroughly inspect and test them to ensure the quality and reliability of the repair. Some of the recommendations that the ASME PCC-2 includes are:
Visual Inspection: A thorough visual inspection of the weld area should be performed to check for surface defects such as cracks, porosity, or incomplete weld fusion.
Non-Destructive Testing (NDT): Depending on the criticality of the repair, non-destructive testing techniques such as ultrasonic testing (UT), radiographic testing (RT), magnetic particle (MT) or liquid-penetrant (PT) should be performed to ensure the integrity of the weld and surrounding material.
5. Specific Considerations for Welded Repairs
Additional considerations depending on the type of pressure equipment and the nature of the damage are also provided in ASME PCC-2:
Crack Repair: When repairing a crack by welding, special attention must be paid to the root cause of the crack – it must be eliminated to prevent recurrence and propagation. Cracks should be removed in their entirety before welding is carried out. The welding process should ensure complete fusion.
Corrosion Damage: For repairs of corroded areas, special welding electrodes or filler materials might be required to combat the corrosion and ensure long-term performance over the useful life of the equipment, or at least until the next inspection interval.
Fatigue Crack Repair: When repairing fatigue cracks due to cyclic loading, the weld should be designed and performed to resist fatigue from future cyclical loading, and the area around the weld must be free from stress concentrators.
6. Post-Repair Considerations
In addition to considerations for choosing and designing adequate repairs, there are some factors that must be taken into account once the repair has been completed. ASME PCC-2 mentions the following aspects to consider post-repair.
Service Conditions: After completion of a welded repair, it’s important to confirm that the pressure equipment is capable of withstanding the operational conditions such as pressure and temperature conditions. The repair should, as a minimum, restore the equipment to its original service capabilities.
Monitoring and Re-Inspection: For critical repairs, especially those under severe service conditions (such as high pressure or temperature=, ongoing monitoring and periodic re-inspection may be necessary in order to detect early signs of failure or degradation in the repaired area.
7. Documentation and Recordkeeping
All welded repairs must be documented, including welder qualifications, welding procedures, material certificates, inspection reports, and if applicable, any post-weld heat treatment data. This documentation is essential not only to ensure compliance with ASME PCC-2, but also to ensure all information regarding the equipment’s repair history is available for future reference in case it requires additional repairs or inspections.
Conclusion:
Welded repairs according to ASME PCC-2 must be carefully planned, executed, and inspected to ensure the structural integrity and safety of the pressure equipment or piping. These guidelines ensure that repairs are done so as to restore the equipment’s functionality, while ensuring safety and maintaining regulatory compliance and durability over time. Proper material selection, welding techniques, inspection, and documentation are critical for the success of a welded repair.
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